Wall forming systems for poured concrete walls have been used for many years. Most forms have been constructed of plywood, steel or aluminum and are typically stripped from the poured concrete wall after the concrete has sufficiently hardened. Regardless of the form material used, an inherent characteristic of these wall forming systems is the use of straight form ties to maintain the position of the forms while concrete is poured and subsequently hardened.
A recent development in this art field is the use of expanded polystyrene panels as form panels. These newer form systems utilize pairs of foam panels which are connected in a parallel, spaced apart relationship by a series of rigid plastic ties. Complete wall form systems are created by stacking the paired foam panels into larger arrays. Concrete is then poured between the panels of the completed foam wall form system. The thickness of the poured concrete walls can be adjusted by the selection and utilization of form ties of appropriate size. Subsequent to concrete hardening these foam panels may be left in place to serve as insulation or may be stripped off to reveal the concrete.
While the aforementioned straight form ties are successful for their intended purpose, it was initially necessary to utilize additional specialized framing and/or form system components at a corner junction where two walls met. U.S. Pat. No. 4,916,879 to P. E. Boeshart (issued Apr. 17, 1990; entitled "Corner Tie") teaches a corner tie for use with foam wall forming systems. The disclosed corner tie has a series of spaced paddles, which are joined in pairs by a single slender spacing strap; the spacing distance between the paddles is equal to the thickness of the foam panels. Similarly joined paddle pairs are inter-connected via a network of slender straps to form the corner tie.
The Boeshart corner tie is deficient in several respects. As taught in the patent, the series of paired paddles do not engage the edges of the foam panels to an appreciable degree, thus stability of the corner components of the foam wall form system is compromised. Moreover, the use of a simple network of slender straps to align the constituent paddle pairs of the corner tie confers a high degree of planar flexibility to the corner tie, thus imparting added instability to the aligned foam panels at corner junctions. As a result, the creation of a stable foam panel wall forming system utilizing these corner ties typically requires the use of smaller foam panels and/or the closer spacing of corner ties (and therefore a greater number of constituent foam panels and/or number of corner ties). Additionally, the use of an external bracing system to reinforce or stabilize the corner sections of the completed wall forming system is generally required.
A second deficiency of this corner tie also arises from the use of the strap network for paddle alignment. The multiplicity of straps cris-crossing the interior space of the corner tie obstructs and impedes the uniform pouring and settling of concrete in the wall forming system. As a result, the poured concrete may be honeycombed with air bubbles. These bubbles or honeycombing in the hardened concrete manifest as a decrease in wall strength and stability
A third deficiency in the Boeshart corner tie is that it cannot be used in conjunction with the traditional reinforcement rods typically used in concrete wall formation.
A fourth deficiency is that this corner tie provides a minimal surface or substrate area to which drywall can eventually be fastened.
As such, there is a clear need for a corner tie which addresses at least some of the aforementioned deficiencies of the current corner ties used in foam wall forming systems.
It is an object of the present invention to provide an improved technique for forming concrete walls.